Modern aircraft utilize contoured structures, e.g. curved metal panels, in a variety of applications including skins, access panels, wing flaps, and fuselage sections. Conventional methods for forming the contoured metal panels include shot peening and laser shock peening. In shot peen forming, a flow of metal, glass or ceramic shot impacts a surface of a metal work piece to elastically and plastically stretch that surface and introduce local low plastic deformation that manifests itself as a residual compressive stress. The combination of elastic and plastic stretching and compressive stress generation causes the metal panel to develop a concave curvature on the shot peened side. Problems arise with shot peening because of process variability. Moreover, shot peening uses small shots typically made of cast iron, cut wire steel, glass or ceramics that often break and need periodic replacement. Handing and disposal of the replaced shot can cause environment problems.
Laser shock peening operates similarly to shot peening, but uses a pulsed laser instead of steel or ceramic pieces to impact the work piece. Laser shock peening, however, requires expensive equipment and time consuming masking/unmasking steps before and after forming.
These methods also increase the surface roughness of the work piece, thereby requiring additional time consuming and costly surface treatment after the contours are introduced into the metal panel. An improved method for forming contoured metal panels would be desirable.